At what temperature does urine freeze?
It’s often said that reading books takes us to new worlds. That’s also true when you write them.
Recently, I was revising a section of a novel I’m working on. It’s set a few centuries after a nuclear war. All the ash and smoke has blocked the sun, leaving the Earth frozen in a nuclear winter. I was working on a bit of dialogue, and I wanted one person to say something along the line of “Does a bear crap in the woods?” but set in their world. I came up with “Does piss freeze?” I wrote that down, but then I wondered at what temperature does urine freeze? This wasn’t just pointless wondering, because I had narrowed this world’s temperature down. I knew it was below 0°C because water is frozen, but it was above -40°C because they had vodka that is still liquid.
To find out at what temperature urine freezes, I went to the internet. There I found a couple different answers: -5°C (It’s about 2/3 of the way down that page) and -120°C. I’m pretty sure the -120°C is wrong.
I did found actual science dealing with freezing urine, but most of the sites I found dealt with freezing “clean” urine so people could use it to pass drug tests. There were discussions on how long it will stay “good,” ways to make it seem “fresh,” as well as warnings about dubious businesses that sell it through the mail. There were even sites for synthetic and even powdered urine.
It was at that point I stopped searching. Given that I’ve had vodka in my freezer without it freezing and some people have frozen urine in theirs, it’s not a problem for my characters to ask “Does piss freeze?” before taking a swig of vodka. Speaking of vodka, I wish I had some in my freezer because I think I need a swig.